Surgical hydrocephalus shunt sleeve for placement in a vertebra



Jan. 17, 1967' M. FEINBERG 3,298,372v

SURGICAL HYDROCEPHALUS SHUNTSLEEVE FOR PLACEMENT IN A VERTEBRA FiledDec. 17, 1963 F I G. 3

INVENTOR Fl G. 5 MAURICE V FEINBERG BY 6% 6M.

ATTORNEYS United States Patent 3,298,372 SURGICAL HYDROCEPHALUS SHUNTSLEEVE FOR PLACEMENT IN A VERTEBRA Maurice Feinberg, 536 Clinton Road,Broolrline, Mass. 02146 Filed Dec. 17, 1963, Ser. No. 331,278 3 Claims.(Cl. 128-350) This invention relates to apparatus for treatinghydrocephalus. It relates more particularly to a surgical device fortreating progressive hydrocephalus of the communicating type by drainingcerebral spinal fluid (CSF) from the subarachnoid space surrounding thebrain and spinal cord into the body of a lumbar vertebra.

Cerebral spinal fluid functions as a shock absorber for the brain andspinal cord and is thought also to carry nutrients to, and metabolitesfrom the central nervous system. A normal person produces between 300and 500 cc. of CSF in a twenty-four hour period. This fluid is normallyabsorbed at various CSF-blood interfaces in and around the subarachnoidspace. The rate of fluid absorption depends on the pressure diflerentialbetween the CSF and the venous system. Physiologically, minor increasesor decreases in the production or absorption of the CSF can be handledproperly by the organism.

Progressive hydrocephalus occurs when there is an excessive pressurebuildup of CSF within the cavities or ventricles located within thebrain. The fluid pressure buildup produces dilation and distention ofthe ventricles, causing the delicate brain tissue to be compressedagainst the inside of the skull. Hydrocepthalic babies heads willenlarge with a rate that is determined by the degree of the malady, andcan possibly result in death. Adults will generally go into a coma orsome degree of paralysis.

The increased fluid pressure within the brain compartments is due eitherto an increase in the production of or a decrease in the absorption ofCSF, or to an obstruction to the CSF pathways. If the pressure buildupis due to an excessive production of or insuflicient absorption of theCSF, but with no obstruction to the CSF pathways in the ventricularsystem and spinal canal, the condition is called communicatinghydrocephalus. If on the other hand, it is due to an obstructionpreventing free communication of CSF between the ventricles and spinalsubarachnoid space, the condition is called obstructive hydrocephalus.This invention deals with the former or communicating type ofhydrocephalus in which the CSF is able to flow freely into the spinalsubarachnoid space.

Prior attempts to reduce or alleviate abnormally high CSF pressurewithin the ventricles have involved the use of ventricular shunts tocontrolledly carry the fluid from the ventricles to one of the variousvenous cavities within the body able to accommodate the fluid. Forexample, ventriculo-caval shunts have been used to carry excess CSF froma ventricle to the internal jugular vein and atrium of the heart. Othershunt devices have been employed to carry CSF to the ureter or variousother body cavities. These procedures have, however, not been entirelysatisfactory because they involve the introduction of'long catheters,tubes or other similar foreign bodies directly into the vascular system,very often resulting in infection such as bacteremia, or obstruction.Also they must employ some sort of valve to prevent back-flow of bloodinto the shunt. The valve often changes its operating characteristics orbecomes wholly inoperative thus requiring additional surgery to effectits repair or replacement. The ventriculo-caval shunts are particularlytroublesome because they must be continually changed or modified, sincethe vascular end of the shunt tends to pull out of position as thepatient grows.

3,298,372 Patented Jan. 17, 1967 ice It is known that the spongy bonemarrow is receptive to and absorbs CSF. Therefore, a potentially farsimpler and safer procedure for reducing abnormally high CSF pressure incases of communicating hydrocephalus would be to drain the fluid fromthe spinal subarachnoid space directly into the cancellous or reticularstructure of a vertebra. In fact, the infusion rate of CSF into themarrow of a lumbar vertebra with a pressure factor of 60 centimeters isin the order of 500 cc. per hour, equal to the amount of CSF producedmainly by the choroid plexus in about 24 hours.

The major difficulty with this type of procedure thus far, however, hasbeen the inability to obtain and maintain a passage for the flow offluid from the subarachnoid space into the body of the vertebra and tomaintain a suflic-iently large CSF-bone marrow-blood interface to absorbenough CSF in order to maintain normal pressure in the CSF system. Forexample, a wedge-shaped or frusto-conical screw, resembling a commonwood screw having a rounded head, was tried. The screw had a smalllongitudinal bore running from end to end and a communicating transversebore of like size located near its narrow end. However, the screw didnot obtain a large enough CSF-blood interface. Further, invariablyduring its insertion, the wedge-shaped body of the screw displaced andcompressed the reticular substance of the vertebra in its path, thusforming around the screw a shell or wall of nonreticular marrow whichwas unable to adequately absorb the CSF and which actually inhibitedwithdrawal of the CSF from the subarachnoid space. The screw sufferedfrom temporary blockage atits orifice, and even became permanentlyblocked by scar tissue, completely clogging the screw bore.Consequently, CSF could not establish contact with the bone marrow andtherefore could not be absorbed, subsequently requiring surgical removalor replacement of the screw.

Most importantly, however, prior screw devices were not satisfactorybecause just as the aforementioned shunts, they took the regulation andcontrol of the absorption of CSF away from the body. CSF pressure nolonger changed with changes in the hydrodynamic characteristics of theblood and CSF, but was made essentially constant by the shunt or screw.

Accordingly, it is a general object of this invention to obtain andmaintain continuous flow of cerebral spinal fluid from the spinalsubarachnoid space into the body of a vertebra.

Another object of this invention is to provide apparatus for treatinghydrocephalus which obtains a large CSF- bone marrow-blood interfacewithin the body of a vertebra and by which the regulation of absorptionand control of CSF pressure are retained by the body.

Still another object of this invention is to provide ap paratus fortreating hydrocephalus which has multiple passages for preventingpermanent and even most temporary blockages of CSF flow.

It is a still further object of this invention to provide apparatus fortreating hydrocephalus which need not be changed or modified as thepatient grows.

It is among the more specific objects of this invention to provideapparatus for treating hydrocephalus which has no moving parts, isrelatively easily inserted into the body, is compatible with the bodyand which may remain permanently in the body even after thehydrocephaletic condition disappears.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others, and theapparatus embodying features of construction, combinations of elementsand arrangements of parts which are adapted to effect such steps, all asexemplified in the following detailed disclosure, and the scope of theinvention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be made to the following detailed description taken inconnection with the accon panying drawing, in which:

FIG. 1 is a diagram showing the application of my apparatus to a patientlying in a prone position;

FIG. 2 is a perspective view of a drainage insert embodying theinvention;

FIG. 3 is a side view, with parts cut away, showing the insertpositioned within the body of the fourth lumbar vertebra;

FIG. 4- is a section along the line 44 of FIG. 3, and

FIG. 5 is a perspective view of a modified form of the invention.

Referring to FIG. 1, a surgical insert indicated generally at isinserted into the body 12 through an incision 14 in the lower back, heldopen by retractors 15.

Access is obtained to the spinal subarachnoid space 16 adjacent a lumbarvertebra, say the fourth, L (FIG. 4) through an incision 17 in theposterior portion of the dura 16a and held open by sutures 19. A hole isthen drilled through the anterior dura wall 16b into the body of thevertebra, forming a deep well 18 in the cancellous substance therein.The well 18 is then flushed and the insert 10 seated snugly therewithin,after which the body incisions 14, 17 are closed. Properly seated, thedevice forms a permanent connection between the spinal subarachnoidspace 16 and the interior of the vertebra L Referring now to FIG. 2 ofthe drawing, the surgical apparatus 10 is constructed of stainless steelor other material which is readily sterilizable, is acceptable to thebody, and produces no electrolytic action therewith. In its preferredembodiment it comprises a thin-walled cylindrical shell 20 open at bothends and having an axial passage 22. The size of shell 20 is determinedby the size of the vertebra into which it is to be inserted, which inturn depends somewhat on the age of the patient. In general, thevertebral volume occupied by shell 20 should be as large as possiblewithout unduly weakening the vertebra. For example, infants canaccommodate a shell 20 approximately 7 inch long and inch wide, whereasin adults, a shell approximately 1 inch long and inch wide has been usedsuccessfully.

A radial flange 24 having rounded top and bottom edges 24a, 24brespectively is formed integrally with one end of shell 20 and extendsan appreciable radial distance out from the side of the shell. Forreasons set forth below, flange 24 has a pair of slotted passages 25,26, between the edges 24a and 24b and extending from the outer surfaceof the flange inwardly to passage 22. A pair of relatively deep, in-lineslots 27, 28 are cut in the top of flange 24 at opposite sides thereofand between passages 25, 26.

Spaced from flange 24 is an array of large, elongated apertures 29,formed in shell 20 and disposed about the circumference of the shell.Apertures 29 extend almost to the opposite end of shell 20 and haveopposite rounded ends 30. The number and width of apertures 29 areselected to provide maximum aperture area with minimum reduction in therigidity of the shell 20. Although other aperture configurations arecontemplated under this invention, the illustrated preferred embodimentof my invention has four identical apertures 29 separated by fouridentical shell portions .31 having approximately the same width as theapertures. The end of shell 20 opposite flange 24 is inwardly tapered at32 to facilitate insertion of the shell 20 into well 18.

In order to permanently secure the insert within the body of a vertebra,a series of screw threads 33 extend out from the shell wall betweenflange 24 and apertures 29. The threads 33 engage the side of well 18 atthe cortex of the vertebra L and cooperate therewith in the manner of .anut and bolt. In some situations, however, particularly with smallinfants whose vertebrae have bone marrow surrounded by cartilage-bone ina 50%5'O% ratio, or 70%30% ratio, it may be desirable to extend thethreads 33 down between the apertures 29 or to utilize a maze ofprotruding knurls in lieu of the threads 33.

Referring now to FIGS. 1 and 3, insert 10 is snugly seated within well18 of the lumber vertebra L; by rotat ing it until the enlarged threadedportion 33 tightly grips the cortical substance found near the surfaceof the vertebra, and the flange 24 presses tightly against the anteriorwall 16b of the dura. This screwing insertion may be facilitated bymeans of a simple T-shaped tool whose :arms fit into the slots 27, 28 inthe top of flange 24. When the insert It) is properly seated CSF flowsfrom the subarachnoid space 16 into vertebra L along the paths indicatedby the solid arrows in FIG. 3. The apertures 29 open onto wide bands ofuncompressed and absorptive cancellous substance 21, creating in thebody of the vertebra a plurality of large area CSF-bone marrow-bloodinterfaces 34 across which the interchange of the CSF and bloodconstituents readily takes place. The effective area of the interfaces34 increases even more after the device has been in place for only arelatively short time, because the cancellous substance 21 tends toexpand somewhat through apertures 29 into shell 20', forming a pluralityof rounded, very absorptive noses 35 (FIG. 4) having a greater surfacearea than the area of apertures 29. The noses 35, however, do notprotrude so far as to block the passage 22 through shell 20.

It is important to note that my invention does not in any way controlthe rate of CSF absorption or flow. For even in an insert 10 suited foran infant, the passage 22 and apertures 29 are more than large enough tohandle the CSF flow in an adult.

Furthermore, even when the shell 20 becomes, in effect, displaced towardthe posterior face 6 of the vertebra L and takes up less of its overallvolume as the patient grows, the apertures 29 still define a sufficientarea of the absorptive cancellous substance 21 near the center of thevertebra to maintain large CSF-bone marrow-blood interfaces.

Thus, the rate of CSF absorption depends entirely on the hydrodynamiccharacteristics of the CSF and blood at the interfaces 34 with theresult that control of CSF pressure and the amount of fluid with itselectrolytes is always retained by the body.

Still referring to FIG. 3, the slotted passages 25, 26 through theflange 24 and the slots 27, 28 in the top of flange prevent eventemporary blockage of the subarachnoid end of the device 10 by providingauxiliary access to bore 22 from the side. If the proximal orifice 22ashould be closed temporarily by a subarachn-oid membrane, CSF is stillable to flow into the passage 22 through auxiliary passages 25-28 alongthe paths indicated by the dotted arrows.

FIG. 5 shows a modified insert particularly suited for infants. It isabout one-half the size of the FIG. 2 device and it comprises anopen-ended cylindrical shell 36 having an integral radial flange 37 atone end. A relatively deep circumferential groove 38 is cut in the sideedge of flange 37, and an array of radial passages 39 extend from thegroove 38 into the interior of the shell. A pair of large elongatedelliptical apertures 40 are formed in the side of shell 36. Apertures 40are spaced from flange 37 and extend almost to the opposite end of shell36. The outside surface of shell 36 between the flange and the aperturesis covered by a multiplicity of raised knurls 41 which engage the sidesof and secure the device in the well 18 in the vertebra.

It is readily apparent from the foregoing that my invention affords asimple, safe procedure for maintaining continuous flow of CSF from thesubbarachnoid space into the body of a vertebra without taking away fromthe body the ability to control or regulate the rate of absorption andthe electrolytes of the CSF. The drainage insert prevents even temporaryinterruption of CSF absorption by providing auxiliary fluid passageswhich are not eifected by blockage. And once inserted into the body, itneed not be removed as the patient grows. In fact, even if the patientshydrocephaletic condition regresses or disappears entirely it can stillremain permanently in the body with no ill effects.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efliciently attained and,since certain changes may be made in the constructions set forth withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limitingsense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

I claim:

1. Apparatus for treating hydrocephalus com-prising a thin-walled,cylindrical shell open at both ends for inserting into the marrow of avertebra, said shell having relatively large inside and outside surfaceareas of comparable extent so as to define a relatively large chamber; aflange at one end of said shell; means on the exterior surface of saidshell for frictionally engaging said vertebra when said shell isinserted thereinto, and a plurality of apertures in said shell, saidapertures extending along a major portion of the length of said shell,and around a major portion of the circumference of said shell, so thatfluid accumulating in said chamber can be rapidly released out throughthe other end of said shell and said apertures into several relativelylarge areas of marrow dispersed throughout the vertebra.

2. Apparatus for treating hydrocephalus comprising an elongated,cylindrical, open-ended shell; a radial flange integral with one end ofsaid shell; a pair of slotted passages extending from opposite side edgeportions of said flange toward each other and communicating with theinterior of said shell; a pair of slots formed in the top of said flangeat opposite sides of said shell, said slots being positi-oned betweensaid pair of passages and extending parallel to the axis of said shell;a plurality of large elongated apertures disposed about thecircumference of said shell, said apertures being spaced from saidflange, and screw threads on the outside of said shell in the regionbetween said apertures and said flange.

3. Apparatus for treating hydrocephalus comprising an elongatedcylindrical open-ended shell for inserting into the body of a vertebra;one or more large apertures in said shell; a radial flange integral withone end of said shell; a relatively deep channel extending around theside edge of said flange; and array of fluid passages extending radiallyfrom the interior of said shell to the bottom of said channel, and meanson the outside of said shell for frictionally engaging the body of saidvertebra when said shell is inserted therewithin.

References Cited by the Examiner UNITED STATES PATENTS 2,431,587 11/1947Schnee 128-348 2,488,232 11/1949 Peeler 468 2,819,719 1/1958 Utley etal. l28-350 OTHER REFERENCES Ziemnowitz: A New Trial of OperativeTreatment of Hydnocephalous Communican Progressivus, Zentralblatt fuerNeurochurige, vol. 10, 1950, pp. 11-17.

RICHARD A. GAUDET, Primary Examiner.

DALTON L. TRULUCK, Examiner.

1. APPARATUS FOR TREATING HYDROCEPHALUS COMPRISING A THIN-WALLED,CYLINDRICAL SHELL OPEN AT BOTH ENDS FOR INSERTING INTO THE MARROW OF AVERTEBRA, SAID SHELL HAVING RELATIVELY LARGE INSIDE AND OUTSIDE SURFACEAREAS OF COMPARABLE EXTENT SO AS TO DEFINE A RELATIVELY LARGE CHAMBER; AFLANGE AT ONE END OF SAID SHELL; MEANS ON THE EXTERIOR SURFACE OF SAIDSHELL FOR FRICTIONALLY ENGAGING SAID VERTEBRA WHEN SAID SHELL ISINSERTED THEREINTO, AND A PLURALITY OF APERTURES IN SAID SHELL, SAIDAPERTURES EXTENDING ALONG A MAJOR PORTION OF THE LENGTH OF SAID SHELL,AND AROUND A MAJOR PORTION OF THE CIRCUMFERENCE OF SAID SHELL, SO THATFLUID ACCUMULATING IN SAID CHAMBER CAN BE RAPIDLY RELEASED OUT THROUGHTHE OTHER END OF SAID SHELL AND SAID APERTURES INTO SEVERAL RELATIVELYLARGE AREAS OF MARROW DISPERSED THROUGHOUT THE VERTEBRA.